Vortex dynamos

We investigate the kinematic dynamo properties of interacting vortex tubes. These flows are of great importance in geophysical and astrophysical fluid dynamics: for a large range of systems, turbulence is dominated by such coherent structures. We obtain a dynamically consistent 2(2)-(1)-dimensional velocity field of the form (u(x, y, t), upsilon(x, y, t), w(x, y, t)) by solving the z-independent Navier-Stokes equations in the presence of helical forcing. This system naturally forms vortex tubes via an inverse cascade. It has chaotic Lagrangian properties and is therefore a candidate for fast dynamo action. The kinematic dynamo properties of the flow are calculated by determining the growth rate of a small-scale seed field. The growth rate is found to have a complicated dependence on Reynolds number Re and magnetic Reynolds number Rm, but the flow continues to act as a dynamo for large Re and Rm. Moreover the dynamo is still efficient even in the limit Re much greater than Rm, providing Rm is large enough, because of the formation of coherent structures

‘Making Sense’ of Urinary Incontinence: A Qualitative Study Investigating Women’s Pelvic Floor Muscle Training Adherence

Urinary incontinence is common and disabling. Pelvic floor muscle training is recommended as first-line therapy for uncomplicatedurinary incontinence. The effects of such behavioural therapies depend in part on adherence. We explored women’s experiences ofincontinence treatment and training adherence in a longitudinal qualitative design. Six women (40–80 years) with stress, urgencyor mixed urinary incontinence symptoms were interviewed twice; once at the start of treatment and again after discharge about 3months later. Interviews were transcribed and analysed using principles of Interpretative Phenomenological Analysis. Experienceswere represented by four themes: Past experiences and meanings of leakage; the supervised treatment period; going on and lookingahead; and the relationship with and experience of others. Variable adherence was explained by how women ‘made sense of it all’.Women with the least difficulty in making sense of their incontinence and in overcoming training inertia had the best self-reportedoutcomes. Conversely, variable adherence, poorer self-reported outcomes, and ambivalence about engaging in treatment werecharacteristic of women who struggled to make sense of their apparently intermittent or unpredictable condition. Helping womenmake sense of incontinence and overcome inertia and ambivalence could improve adherence, but this may be a prolonged process

Are we teaching our students what they need to know about ageing? Results from the National Survey of Undergraduate Teaching in Ageing and Geriatric Medicine

Introduction - Learning about ageing and the appropriate management of older patients is important for all doctors. This survey set out to evaluate what medical undergraduates in the UK are taught about ageing and geriatric medicine and how this teaching is delivered. Methods – An electronic questionnaire was developed and sent to the 28/31 UK medical schools which agreed to participate. Results – Full responses were received from 17 schools. 8/21 learning objectives were recorded as taught, and none were examined, across every school surveyed. Elder abuse and terminology and classification of health were taught in only 8/17 and 2/17 schools respectively. Pressure ulcers were taught about in 14/17 schools but taught formally in only 7 of these and examined in only 9. With regard to bio- and socio- gerontology, only 9/17 schools reported teaching in social ageing, 7/17 in cellular ageing and 9/17 in the physiology of ageing. Discussion – Even allowing for the suboptimal response rate, this study presents significant cause for concern with UK undergraduate education related to ageing. The failure to teach comprehensively on elder abuse and pressure sores, in particular, may be significantly to the detriment of older patients

Polarimetric Observations of 15 AGNs at High Frequencies

Original paper can be found at: http://www.astrosociety.org/pubs/cs/328.html--Copyright Astronomical Society of the PacificWe have obtained total and polarized intensity images of 15 AGNs with the VLBA at 7 mm at 17 epochs from 25/26 March 1998 to 14 April 2001. The VLBA observations are accompanied at many epochs by simultaneous mea- surements of polarization at 1.35/0.85 mm as well as less frequent simultaneous optical polarization measurements. We discuss the similarities and complexities of polarization behavior at different frequencies along with the VLBI properties

Energetic impact of size-selected metal cluster ions on graphite

We have investigated the impact of size-selected metal cluster ions (Agn-) on a covalently bonded substrate (graphite) over the energy range 15–1500 eV by a combination of scanning tunneling microscopy and molecular dynamics simulations. The key result is that the fate of the cluster (penetration into the surface versus diffusion and aggregation on the surface), at intermediate energies, depends on the lateral localization of the cluster kinetic energy at specific surface sites and thus, for small clusters, on the orientation of the cluster and the target substrate site

Behaviour of the Blazar CTA 102 during two giant outbursts

Blazar CTA 102 underwent exceptional optical and high-energy outbursts in 2012 and 2016-2017. We analyze its behaviour during these events, focusing on polarimetry as a tool that allows us to trace changes in the physical conditions and geometric configuration of the emission source close to the central black hole. We also use Fermi gamma-ray data in conjunction with optical photometry in an effort to localize the origin of the outbursts.AST-1615796 - Boston Universit

Topological Charged Black Holes in High Dimensional Spacetimes and Their Formation from Gravitational Collapse of a Type II Fluid

Topological charged black holes coupled with a cosmological constant in $R^{2}\times X^{D-2}$ spacetimes are studied, where $X^{D-2}$ is an Einstein space of the form ${}^{(D-2)}R_{AB} = k(D-3) h_{AB}$. The global structure for the four-dimensional spacetimes with $k = 0$ is investigated systematically. The most general solutions that represent a Type $II$ fluid in such a high dimensional spacetime are found, and showed that topological charged black holes can be formed from the gravitational collapse of such a fluid. When the spacetime is (asymptotically) self-similar, the collapse always forms black holes for $k = 0, -1$, in contrast to the case $k = 1$, where it can form either balck holes or naked singularities.Comment: 14 figures, to appear in Phys. Rev.